Process of making heptamethine dyes



Patented Oct. 4, 1938 PROCESS OF; MAKING HEPTAMETHINE 'DYES Walter Zeh,JDes sau in Anhalt, Germany, assignor to Agi-a Ansco Corporation, Binghamton, N.-Y. a corporation of New-York N oQDrawing. Applicati .No..725;,214. In Ge Claims.

My present-inventionrrelates to dyes of the polymethine series.

oneflofwitsp-objects. is to i provide -a .process: of

producing; dyes from the :polymethineseries; An-.

5 other object are thedyesfoftthe polymethine se-- ries: which haverproved-to be valuable sensitizers.

Further: objects will ;be seen from the detailed thexfacttthata an extraordinary great number of suitableudyes is now available, but also in the fact, that .by suitably/,zcombining different quazmgternary iammonium-s salts -:of heterocyclic. bases containing in M'IJOSitiOH to the nitrogen atom a methylrigroup capable of reaction nearly any de;- sired maximum of sensitization may be obtained in theiinfra ed. portionigof the'spectrum. Thus 5, it is possible to adjust the sensitivity of :the emul-.. 1

sion according to requirement.

For: the... preparation of the unsymmetrical heptacarbocyanines. there is first made an intermediate product by condensing in the presence 40 ,of a ..s-phenylimidow-z r-pentadiene hydrohaloe,

genide... As alkaline. .condens ing agent I have found suitable, for instance, primary, secondary and tertiary amines, suchas methylamine, di-

ethylamine, trimethylamine, triethylamine, pi-" 60., -that tofnthe ibase-twhichl is used, because. an ina on May 11, 1934, Serial rmany May. 18, 1933 creasing amount of condensing agent promotes the formation of symmetrical dye from which the intermediate product must be separated,

usually by physical means (crystallization, decocting). each condensing agent can easily be determined by experiment. Condensing Iagents whichlmay casually be applied in excess so that nevertheless the formation of intermediate product occurs are'the amines.- In-case of using-pyridine. or condensing agents of similar action which simultaneously are usedas solvents, there maybe used an excess for obvious reasons. Of the above anilido compounds the N-methyl compounds have proved particularly suitable insome cases.

It is advisable to use an amount of the anilido compound substantially exceeding the quantity equivalent'to that of the base; preferably there is used a more than per cent excess-in order to avoid as. far as possible the undesired forma-.

tion of symmetrical dye. l

When .using, for example, benzothiazole as the heterocyclic base, the reaction between2-methylbenzothiazole iodo alkylate and e-PhBIlYlill'lidO-ae phenylamido-(m -pentadienehydrobromide probablytakes place according to the following for- .mula;

8 p of an alkaline condensing agent equivalentportions of a quaternary ammonium salt of a heter- ,33-6H +O H NH-CH=CHCH=CH-CH=N-CeHs .ocyclic base containing in oc-IJOSitiOIl to the nitrogen atom a methyl group capable of reaction and R Y I 1 6\4/\ }oH=0H-0H=0H-0H=0H-NH-O6H5+oa115NHz+HBr In this mannerthe intermediate hexamethine dyestuff corresponding with the above formula is formed, which is then converted with the quaternary ammonium salt of' another heterocyclic base-containing a reactive. methyl group, as for examplequinaldine iodo alkylate, in the presence of .-an alkaline condensing agent, according to the following formula:

Thisprocess may be carried outwith all hetero-.

The most suitable-amount to be used of" cyclic bases containing a reactive methyl group, in particular with monoand polynuclear thiazoles, selenazoles, 2- and 4-methylquinolines. For example pyridine, piperidine ethanolamines, alkylamines and sodium ethylate are suitable alkaline condensing agents.

The heptamethinecyanine dyestuffs obtained according to the present invention have the following general formula, from which the comprehensive application of this new process may be recognized:

Y and Z are S, Se, CH=CI-I- R1, R2, R3, R4 represent hydrogen, alkyl or aryl, or, if desired, R1Rz and R3R4 in combination represent unsubstituted or substituted phenylene, naphthylene or other polynuclear arylene groups. (Alkyl, aryl, alkoxy, thioalkyl, selenoalkyl, substituted or unsubstituted amino groups belong to the substituents contemplated.)

For the unsymmetrical character of the dye it is necessary, that Y and Z or R1, R2 and R3, R4 are different from each other.

R5 and R6 represent alkyl, 1

X represents an anion for'instance, Cl, Br, I, C104, CH3-C6H4-SO3, CH3SO1, C2H5--SO4.

The quinoline nucleus which results in case of Y being CI-I=CH-- may be linked to the polymethenyl chain in 2 or 4 position. The hydrogen atoms of the heptamethine chain may be substituted by alkyl groups, as for example methyl or ethyl.

In the general formula Y and Z may represent sulfur, selenium or the vinyl group CH=CH. In the case of dyes in which, for instance, a thiazole nucleus and a selenazole nucleus are linked together by a heptamethenyl chain R1, R2, R3 and R1 may represent hydrogen, or they may represent alkyl, or aryl or carbethoxy. In combination RIR2 and R3R4 may represent phenylene, or naphthylene or a polynuclear arylene group, for instance, the corresponding radical of anthracene, chrysene, fiuorene or acetnaphthene. In the case of Y being sulfur, Z being selenium, R1R2 and R311; being phenylene, the dye is a [benzthiazole- (2) l] [benzselenazole- (2!) --hep ta methinecyanine. If Y is selenium, Z is sulfur, R1R2 is phenylene, and R3 andR4 are hydrogen the dye is a [benzselenazole-(Z) l-[thiazole-(2) heptamethinecyanine. the dyes which are contemplated by the invention but also the nomenclature. In the case of Y being CH=CI-I, Z being sulfur and R1,R2,R3,R4 being hydrogen, there result dyes in which a pyridine nucleus is linked together with a thiazole nucleus by a heptamethenyl chain. If Y is CI-I CI-I, Z is sulfur, R1R2'is phenylene, R3 and R4 are hydrogen, there results a dye in which a quinoline nucleus is linked together with a thiazole nucleus by a heptamethenyl chain and is called a [quinolinel-[thiazole-(2)l-heptamethinecyanine. The quinoline nucleus may be linked in 2 or 4 position. The benzene rings and so on fused on the heterocyclic rings containing a nitrogen atom may be substituted for instance by alkyl, alkoxy, aryl, halogen, substituted or unsubstituted amino groups. The radicals R5 This not only illustrates and Rs linked to the nitrogen atoms of the heterocyclic rings linked together by the heptamethenyl chain represent alkyl. X represents an anion, for instance those disclosed above.

The dyes are obtainable according to the desired solubility in form of the bromide, iodide, perchlorate etc. and are used in a quantity such as is usual for the known sensitizing dyes. This quantity may amount to about 0.5 to 2 milligrams per 1 kg. of emulsion ready for being cast which contains about 9 per cent of gelatin, 4.5 per cent of silver halide and the rest water. However, I do not wish to limit my invention to the quantities just indicated, the most suitable amount will in each case be found by a few comparative experiments. The dyes may be added to the emulsion in form of solutions. Suitable solvents are the alcohols, for instance, methyl or ethyl alcohol which may be used anhydrous or diluted with water. The dyes are applied to the emulsion during any stage of its production, however, they are preferably added to the finished emulsion before casting.

The dyes may likewise be added to the emulsion by bathing the finished photographic material in a bath in which the dye is dissolved. Such a treatment may be as follows: The photographic material to be sensitized is bathed in a solution containing 1 milligram of [ZS-ethylbenzselenazole-(2)l [1 ethyl-quinoline (4) lheptamethinecyanine iodide in 500 to 1000 cc. of an aqueous solution of methanol of 50 per cent strength for about 5 minutes. The material is then dried, whereupon it is ready for use.

The following examples serve to illustrate the invention.

Example 1.In order to obtain [3-ethyl-benzthiazole- (2) [3 ethyl-{naphtho 1.2': LS-thiazole}-(2) l-heptamethinecyanine iodide having the formula:

15 grams of 2-methylbenzthiazole ethiodide are boiled with 20 grams of ephenylimido-a-phenylamido-a, -pentadienehydrobromide in 50 cc. of

alcohol and then mixed with 1.5 cc. of piperidine;

the mixture is boiled for further 30 minutes and then cooled. By adding 50 cc. of a solution of potassium iodide of about 2 per cent strength, the dyestuff (intermediate product) corresponding probably with the formula:

H C2115 I tamethinecyanine iodide separates on addition of about cc. of a 5 per cent solution of potassium iodide; brownish green little rods crystallize from alcohol.

Incorporated in a silver bromide emulsion containing about 4 per cent of silver iodide the dye imparts to it a range of sensitivity from about 65[LM to 930 with a maximum of about 830 l.

' Example 2. [3-ethyl-benzthiazole- (2) l-[3- ethyl 5.6 dimethyl benzselenazole (2) l heptamethinecyanine iodide having the formula:

Calls is obtained by heating'LS grams of phenylamidol-ethyl benzthiohexamethine iodide (intermediate product), obtained according to Example 1, in 10 cc. of alcohol together with 1 gram of lepidine ethiodide until the whole is dissolved and, after adding -1 cc. of diethylamine, boiled until the reaction mixture assumes a dark green color. By the addition of 5 cc. of a 10 per cent aqueous solution of sodium perchlorate, the dye separates. It crystallizes from alcohol in small brownish red plates.

Incorporated in a silver bromide emulsion containing about 2 per cent of silver iodide the dye imparts to it a range of sensitivity from about tion of potassium iodide. alcohol yields dark green crystals which in al- 650,1l/L to 920 with a maximum of about 825 l. Example -4.'In order to produce the dyestufi corresponding with the forumla:

.7 i 6 Se 17.5 grams of 2- methylbenzselenazole ethiodide and 20 grams of e-phenylimido-u-phenylamido-a, -pentadiene hydrobromide' are dissolved in 50 cc. of alcohol in the warmth, mixed with 1.5 cc. of piperidine and boiled for half an hour. After cooling, the resulting vphenylamido-l-ethylbenzselenohexamethine iodide is precipitated by the addition of 50' cc. of a 5 per cent aqueous solu- Recrystallization from about 638,114!

4 grams of this intermediate product, 2.5 grams of 2,4-dimethylthiazole ethiodide and 2 cc. of diethylamine are boiled in 10 cc. of alcohol until 7 the mixture assumes an intense blue color. After cooling, the dyestufi is precipitated by adding 3 cc. of a 10 per cent solution of sodium perchlorate. Druses of green crystals are obtained by recrystallizing from alcohol.

Incorporated in a silver bromide emulsion containing about 2 per cent of silver iodide the dye imparts to ita range of sensitivity from about 600 to 880/L/L with a maximum at about 785 Example 5.-In order to obtain [3-ethyl-benzselenazole-(2.)'l-[1-ethyl-quinoline-(4) l :hep tamethinecyanine iodide corresponding with the following formula:

-Se l 1 4,5 grams of 2-methylbenzselenazole ethiodide and 5 grams of e-N-methylphenylimido-a-N- methylphenylamido-u mentadienehydrobromide are boiled for 30 minutes in 25 cc. of alcohol, while adding 1 cc. of triethanolamine. On cooling, the hexamethine dye corresponding probably with the formula:

separates in green needles. The alcoholic solution of the dyestuiT has an absorption maximum at about 610/.LIL.

2 grams of the dyestuff (intermediate product) thus obtained and 1.5 grams of lepidine iodo ethylate are dissolved in 20 cc. of alcohol in the warmth and boiled after the addition of 1 cc.

of triethylamine until the separation of [Ii-ethylbenzselenazole (2) ]-[1 ethyl-quinoline (4) lheptamethinecyanine iodide commences. The dyestuff crystallizes from alcohol in brown crystals.

Incorporated in a silver bromide emulsion containing about 2 per cent of silver iodide the dye imparts to it a range of sensitivity from about 660 to 930 with a maximum at about 825HM.

Example 6.In order to produce [3-ethyl 5- m e t h o x y-benzselenazole(2) l-[3-ethyl-5-diethylamino benzthiazole (2)] heptamethine cyanine iodide having the following formula:

the intermediate dyestufi corresponding probably with the following. formula:

is produced from 2-methyl-5-methoxybenzselencoholic solution have an absorption maximum at azole ethiodide according to Example 5 and has an absorption maximum of about 615 1 2 grams oi this dyestuff are dissolved with 1.5 grams of 2-methyl-5-diethylaminobenzthiazole ethiodide in cc. of hot alcohol and gradually mixed with 4 cc. of an alcoholic solution of sodium ethylate (containing 3 per cent of sodium) and kept boiling, until the mixture assumes a bluish green color. The dye which is precipitated on cooling crystallizes from alcohol in copper-brown crystals.

Incorporated in a silver bromide emulsion containing about 4 per cent of silver iodide the dye imparts to it a range of sensitivity from about 700 to 900 with a maximum at about 855 Exampl 7.In order to obtain [3-ethyl-benzthiazole-(Z) l-[3-e t h y 1-{naphtho-2.1:4.5-thiazo1e}- (2) l-a-methyl-heptamethinecyanine iodide corresponding with the formula:

4 grams of Z-methylbenzthiazole ethiodide are boiled with 5 grams of ephenylimido-a-phenyla m i d o-' -methyl-u,' -pentadiene hydrobromide (obtained from aniline, -picoline and cyanogen bromide analogously to the unsubstituted compound, according to the process described by Konig, in Journ. f. prakt. Chemie, 69, p. 105) in cc. of alcohol, mixed with 0.8 cc. of piperidine and heated for 30 minutes on the steam bath. After cooling the dark blue mixture, 20 cc. of a 5 per cent aqueous solution of potassium iodide are added, and the hexamethine dye (intermediate product) formed and corresponding with the following formula:

is filtered off. The dyestuff crystallizes from alcohol in blue needles. The alcoholic solution has an absorption maximum at about 620 1 gram of the intermediate product and 0.8 gram of 2-methyl-[n.aphtho-2.l':4.5-thiazolel ethiodide are dissolved in 10 cc. of boiling alcohol and kept boiling for 10 minutes, while adding 0.7 cc. of diethylamine. The resulting [3-ethylbenzthiazole- (2) l [3' ethyl-(naphtho-2.1': 4.5- thiazole) (2) 6 methyl heptamethinecyanine iodide is recrystallized from alcohol thereby yielding druses of dark brown crystals.

Incorporated in a silver bromide emulsion containing about 4 per cent of silver iodide the dye imparts to it a range of sensitivity from about 630 to 920/.LM with a maximum at about 84:0,LLIL.

Example 8.In order to produce [3-ethyl-6- In e t h y l-quinoline-(2) l-[3-ethyl-benzthiazole- (2) l-heptamethinecyanine iodide having the following formula:

5 4 HaC- 6 3 C2115 I (IJZHB a mixture of 4 grams of toluquinaldine iodo ethylate and 5 grams of e-N-methylphenylimidoa-N-methylphenylamido-a-' -pentadiene hydrobromide are boiled in cc. of alcohol and, after the addition of 1 cc. of diethylamine kept for about 5 hours on the steam bath. After cooling, the reaction product which separates is recrystallized from alcohol. The dye (intermediate product) obtained corresponds probably with the formula:

HaC

N/ CH=CHCH=OHCH=CHIII- czHs \I CH8 and forms green crystals, the alcoholic solution of which has an absorption maximum at about 605;:44.

2 grams of the dye (intermediate product) thus obtained are dissolved with 1.5 grams of Z-methylbenzthiazole ethiodide in 10 cc. of boiling alcohol and gradually mixed, while boiling, with about 3 cc. of a 3 per cent solution of sodium ethylate. Boiling is continued until the mixture assumes a greenish blue color. The dye crystallizes from alcohol in green needles.

Incorporated in a silver bromide emulsion containing about 2 per cent of silver iodide the dye imparts to it a range of sensitivity from about 630 to 930/.L/L with a maximum at about 828,14

Example 9.In order to produce the dyestuff having the formula:

0.5 cc. of triethanolamine is added to a boiling solution of 4 grams of 2,5,6-trimethylbenzthiazole ethiodide and 5 grams of e-N-methylphenylirnido a N-methylphenylamidow -pentadienehydrobromide in 25 cc. of alcohol, and boiling continued for one hour. On cooling, the intermediate dyestuff separates in form of bluish green needles. 1 gram of this dyestuff is heated for 10 minutes with 1 gram of 2.4-dimethylthiazole ethiodide in 10 cc. of alcohol, while adding 1 cc. of diethylamine, until the mixture assumes a bluish green color. On cooling, the dyestuff crystallizes in brownish green crystals.

Incorporated in a silver bromide emulsion containing about 2 per cent of silver iodide the dye imparts to it a range of sensitivity from about 600 to 910 with a maximum at about 800 Example 10.--In order to produce [3-ethyl-5- diethylamino-benzthiazole-(2) l-[3-ethyl-q u i no l i n e-(4) l-heptamethinecyanine perchlorate corresponding with the following formula:

0 I lN i, .grams-rof 2.-methyl1-5 diethylamidobenzthiazole ethiodide. are boiled withfigramsof (N-methyl- ,..phenylimido) )1 a: (Nrmethylphenylamido) a,'y- ,apentadiene.hydroebromidein 20 cc. of alcohol,

5 while adding about,1 .cc. of .triethanolamine,

until the mixture assumes a dark blue color. The resulting hexamethine dyestuffiintermediate product) corresponding probably with the formula:

is I precipitated in green floccules, while adding -:grams-oflepidin ethiodide in'lO cc. of alcohol,

while gradually adding about 1" cc. of diethyl- 1-:amine,1until.the mixture assumesa greenish blue icolor; The dyestuff separates in dark floccules on'the addition f11Q cc. of a solution 'of sodium perchlorate. ;.A bluish-black crystalline powder .is .obtained by recrystallization from alcohol. Incorporated in a silver bromide emulsion. containing'about? per cent of silver iodidethe dye imparts to it a range of sensitivity from about 650 to 1000 with a maximum at ab0ll13 365mm Example LIL-Theintermediate product 0bntained-according.toExample 10 may be converted .according tothe manner specified therein-by ,means ,;0f .2.l dimethylthiazole methiodide into 1 l3 gram 40f N-ethyl-G methoxybenaselenohexa- .-..methine-N-methylanilido iodide, as obtained according-to Example 6, and 1 gram of 2-methyl- .fl-phenylthiazole methiodide. are boiled for about 5-minuteain cc. of alcohol, while adding 1 cc.

- of an alcoholic solutionof trimethylamine of-50 The dyeseparates in form of per cent strength. a green crystals. I Incorporated in asilver bromide emulsion con- ..taining about. 2- per cent of .silver iodide 'the .dye impartsto it a'rangeyofsensitivity from benzs'elenazole-(2)1-[3-ethyl-pyridine-(2) l-heptamethinecyanineperchlorate corresponding prob-v ably with the formula:

CzHs C104, (52H!) 1 gram of "N-ethylbenzsele nohexamethine N- methylanilido iodide (made according to Example5) and 1 gram of uepicoline ethiodide are carefully boiled in 5 cc.,of pyridine, until the mixture .assumes a dark blue color. When adding 5 cc. of an aqueous solution of sodium perchlorate of 10 per cent strength, the dye is precipitated in blue floccules.

incorporated in a silver bromide emulsion containing about 2 per cent of silver iodide the dye imparts to it a range ofsensitivity from about 550ml. liq 81.0 114; Witha maximum at about 740,044.

"Example 14..-In- [order to obtain [3-ethyl-5- e'thoxy 6 methyl benzthiazole -(2) 1-[3-ethyl- 5.fidimethyl benzselenaZole-i(2) heptamethinecyanine iodide probably having the following for- [3,-e :t hyl-5.-.diethylaminorbenzthiazole- (2) [3- mula;

Hao- -s se- 7 6 0113 I l i I l 5" 2. 5 $545 H50,0 o1a o11 (DH-CH CH OH CH'\I?I/\1/ CH3}? CzHs I CQHQ ethy1-4-m e t h y l-thiaz ole-(2) l-heptamethinel;. --grams of 2.6edimethyl-5-ethoxybenzthiazole r0 cyanine perchlorate corresponding probably with -.ethiodide and 5 g ams of E-N-methyl-phenylithe formula: y Dheny1amido-a,'y pentadiene -S v S CB ":4 till... (H5C:)2N 4 g -0H= JH0H=0H-011=o11011= 3 5: CgH5 \C104 7 (I311: v Recrystallization from alcohol yieldsbronze colhydro-bromide-are heated with 15 cc. of pyridine .50 ored crystals. for about 1 'hour onthe steam bath, or the mix-- Incorporated in a silver bromide emulsion con- I ture-is boiled fora-short time, say 3 to 5 minutes. taining about 2 per cent of silver iodide the dye The separation of the intermediate product may imparts to it 'a range of--sensitivity from about -be'completed by the-additionof about 10 cc. of 600,1t to920p wltha maximum at about 820 saysolution of potassium iodide. P The intermedi- 5 Example -12.In order yto -obtain [3 -ethyl-'5- ate dyestuff having the following formula:

' methoxy-benzselenazole- (2) [3-ethy1-4-phenyl- H30 thiazole-(2) l-heptamethinecyanine iodide corre-- s sponding probably with the following formula: g

CH=OHCH=OHCH=CHNO&H5 W70 7 Se H6020 ./N (LJHS E 6 1 I1 5 C2H5 I H300 f c crystallizes from alcohol in form of a blackish 5 green crystal powder. The alcoholic solution of GsHt l I rtheicompound has .an. absorption maximum at about 610 1 gram of the resulting'interme- Emwmple, 13.- In. orderto-produce [3-ethylv mediate product in admixture with the same amount of 2.5.6-trimethylbenzselenazole ethiodide is boiled in 10 cc. of alcohol while adding 0.5 cc. of triethanolamine, until the dyestuff is precipitated in green crystals.

Incorporated in a silver bromide emulsion containing about 4 per cent of silver iodide, the dye imparts to it a range of sensitivity from about 750 to QOOIL/L with a maximum at about 840 Example 15.-In order to obtain [3-ethylbenztliiazole- (2) [3-ethyl 5 carbethoxy-thiazole-(2)l-heptamethinecyanine iodide corresponding probably with the following formula:

the intermediate dyestuff corresponding probably with the following formula:

is precipitated in form of green crystals. The

1 gram of N-ethylbenzthiohexamethine-N-methylanilido iodide as obtainable from 2-methylbenzthiazole iodo ethylate and e-N-methyh phenylimido-a-N-methylphenylamido bromide in alcoholic solution analogously to the method described in Example 10 and 0.7 gram of 2.4-dimethyl-5-carbethoxythiazole methiodide are dissolved in 10 cc. of alcohol in the warmth and boiled for about 5 minutes after the addition of about 1 cc. of diethylamine. On cooling the dyestuff separates in form of a bluish black crystalline powder.

Incorporated in a silver bromide emulsion containing about 2 per cent of silver iodide, the dye imparts to it a range of sensitivity from about 650 to 900 with a maximum at about 800/141 Example 16.[3-ethyl benzthiazole- (2) l- [3- ethyl {tetrahydronaphtho 2'.l' :45 thiazole}- (2)1-heptamethinecyanine iodide corresponding with the following formula:

alcoholic solution thereof has an absorption max- -imum at about 655 1 gram of this intermediate product and 1 gram of 2-methyl-6-methoxybenzthiazole ethiodide are heated, until dissolution occurs, and then mixed with 2 cc. of an alcoholic solution of trimethylamine of about 50 per cent strength, whereby the color changes to green. After cooling [l-methylquinoline- (4) [3-ethyl-S-methoxy-benzthiazole- (2)l-heptamethinecyanine iodide. is precipitated as a bluish black crystalline powder.

Incorporated in a silver bromide emulsion con-' taining about 2 per cent of silver iodide, the dye imparts to it a range of sensitivity from about 650 to 950/1. with a maximum at about 830 Example 18.In order to obtain [1-ethy1quinoline 2)1-[3.5 dimethyl thiazole-(Z) l-heptais obtained in the manner described in Example 15, from Z-methyl-tetrahydronaphtho-2.1:4=.5- thiazole ethiodide and V N-ethyl-benzthiohexamethine anilido iodide.

Incorporated in a silver bromide emulsion containing about 4 per cent of silver iodide, the dye imparts to it a range of sensitivity from about 670 to 880,114 with a maximum at about 615 Example 17.In order to obtain [l-methylquinoline- (4) l- [3-ethyl-6-methoxy-benzthiazole- (2)1-heptamethinecyanine iodide corresponding probably with the following formula:

4 grams of lepidine methiodide and 5 grams of e-Nmethyl-phenylimido a N methylphenylamethinecyanine iodide corresponding probably with the following formula:

boiled for 2 hours in cc. of alcohol while adding 2 cc. of triethanolamine.

On cooling, N-ethyl solution of trimethylamine of 50 per cent' imparts to it arange of sensitivity from about VOO to- 900 with a maximum at about 84IO/L/L. Example 19.-The dye [3-ethyl-5-ethoxy-benzselenazole -(2) l-[3'-ethyl-5-chloro 6 methoxybenzthiazole (2)]- heptamethinecyanine iodide corresponding to the formula:

diate product corresponding probably with the formula: V

OH. OzH5 I a separates in form of blue-black flakes. Recrystallization from alcohol yields steel blue little rods. "The alcoholic solution of the compound has an absorption maximum at about 605 ,1 gram of the intermediate product is boiled with 0.8 gram of 2-methyl-5.6-methylene-dioxybenzthiazole ethiodide in 10 cc. of alcohol while adding about 1 cc. of diethylamine, and boiling is continued for about 10 minutes. The dye separates in form of green crystals.

7 6 OOH:

may be produced as follows:

4 grams of Z-methyl-5-ethoxy-benzselenazole ethiodide are dissolved with 5 grams of e-N- methyl-phenyl imido- N-methyl-phenylamido wr -pentadiene hydro-bromide in 30 cc. of alcohol. After the addition of 0.7 cc. of benzylamine the mixture is heated to 100 C. for about 3 hours. On cooling the intermediate product separates in CaHa Incorporated in a silver bromide emulsion containing about 4 per cent of silver iodide, the-dye imparts to it a range of sensitivity from about GOO/1,, to 900 1., with a maximum at about 825/.LIL. Example 21.-The dye [3-ethyl-5-ethoxy-6- methyl benzthiazole (2)'l [3-ethyl -{acenaphtheno-5.4 :4.5-'thiaz'ole}- (2) l-heptamethinecyanine iodide corresponding with the formula:

form of green crystals. Recrystallization from alcohol yields green leaves. r 1.1 grams of the intermediate product,10.8 gram of 2- methyl-5-chloro-6- methoxy benzthiazole ethiodide and 10 cc. of alcohol are heated, while adding 2 cc. of an alcoholic solution of trimethylamine of 50 percent strength, until the dye separates in form of crystals. Recrystallization from methanol yields brownish green crystals.

Incorporated in a silver bromide emulsion containing about4 per cent of silver iodide, the dye imparts to it a range of sensitivity from about 670 to 900w, with a maximum at about 830 Example 20.--The dye [3-ethyl-benzthiazole- (2)l-[3-e1thy1-5.6 methylene .dioxy benzthia zole-(2) l-heptamethinecyanine iodide corre-' sponding with the following formula:

may be prepared as follows: V r

2 grams of 2.6-diethyl-5 ethoxy-benzthiazole ethiodide. are heated with 2.5 grams of e-N- methyl-phenylimido w pentadiene hydro-bromide in 20 cc. of alcohol until dissolution occurs, and then there are added 2.5 cc. of an alcoholic solution of sodium ethylate of 5 per cent strength. The yellow red solution changes its color immediately to blue-red and the intermediate product corresponding probably with the following formula: r 7

separates in form of green crystals. Heating is is obtained by heating 4 grams of 2-methylbenz- V thiazole ethiodide with 5 grams of e-N-methylphenylimido-a-N-methyl phenylamido-w -pentadiene hydro-bromide in 20 cc. of alcohol to 100 C. until the mixture assumes a dark blue color (about 3 hours), while adding 2 cc. of an alcoholic strength. 0n addition of about 5 cc. of a 5 per cent solution of potassium iodide the intermecontinued for a short period and the product is filtered off. The alcoholic solution of the compound has an absorption maximum at about 610,411,, 7

1 gram of the intermediate product and 1 gram of Z-methyl acenaphthenethiazole ethiodide when heated in 15 cc. of alcohol with theaddition of 1 cc. of diethylamine yield the above dye which separates in form of crystals on the wall of the reaction vessel. Recrystallization from alcohol yields green crystals.

Incorporated in a silver bromide emulsion containing about 4 per cent of silver iodide, the dye imparts to it a range of sensitivity from about 690 to 930 with a maximum at about 850114! Example 22.The dye [3-ethyl-benzthiazole- (2) l-[3-ethyl-{anthraceno 1 .2' :45 thiazole}- (2) l-heptamethinecyanine iodide corresponding with the formula:

I CaHs I CZHB may be obtained by making the intermediate product as disclosed in Example 20 and using 1 cc. of monomethylamine as condensing agent. 1 gram of the intermediate product, 1 gram of 2- methyl- [anthraceno- 1'.2' 24.5-thiazole-p-toluenesulfo ethylate (2-methyl-anthrathiazole p-toluenesulfo ethylate) and 1 cc. of diethylamine are boiled in 10 cc. of alcohol for about 10 minutes. On cooling the dye separates in form of greenish brown crystals. From alcohol the dye crystallizes in form of a copper colored crystal powder.

Incorporated in a silver bromide emulsion containing about 2 per cent of silver iodide, the dye imparts to it a range of sensitivity from about 700 l to 900 with a maximum at about 835 What I claim is:

1. The process of producing an unsymmetrical heptamethinecyanine which comprises reacting on a quaternary ammonium salt of a nitrogenous heterocyclic base selected from the class consisting of w-methyl-thiazoles, a-methyl-selenazoles, m-methyL-quinolines and -methyl-quinolines with an ephenylimido-a-phenylamido-axypentadiene hydrohalide in the presence of an amount of alkaline condensing agent not greater than the quantity equivalent to that of the base, and condensing the intermediate product thus obtained with another quaternary ammonium salt of a nitrogenous heterocyclic base selected from the class consisting of ao-methyl-thiazoles, a-methyl-selenazoles, a-methyl-quinolines and "ymethyl-quinolines in the presence of an alkaline condensing agent.

2. The processor producing an unsymmetrical heptamethinecyanine which comprises reacting on a quaternary ammonium salt of a nitrogenous heterocyclic base selected from the class consisting of oc-IllfithYl-thlELZOlGS, a-methyl-selenazoles, a-Il'lBthYl-Qllll'lOllllES and y-methyl-quinolines with an amount of e-phenylimido-a-phenylamido-w -pentadiene hydrohalide substantially surpassing the quantity equivalent to that of the base in the presence of an amount of alkaline condensing agent not greater than the quantity equivalent to that of the base, and. condensing the intermediate product thus obtained with another quaternary ammonium salt of a nitrogenous heterocyclic base selected from the class consisting of a-methyl-thiazoles, a-methy l-selenazoles, a.- methyl-quinolines, and 'y-methyl-quinolines in the presence of an alkaline condensing agent.

3. The process of producing [3-ethyl-benzselenazole- (2)'lj- [3-ethy1-4-methyil thiazole-(2) heptamethinecyanine iodide which comprises reacting on Z-methyl-benzselenazole ethiodide with e-PhEllYl-ilflldO a phenylamido-ax -pentadiene hydrobromide in the presence of an amount of piperidine not greater than the quantity equivalent to that of said base, and condensing the intermediate product thus obtained with 2.4-dimethylthiazole ethiodide in the presence of diethylamine.

4. The process of producing [3-ethyl-benzselenazole (2) 1- [1 ethyl-quinoline-(4) l-heptamethinecyanine iodide which comprises reacting on Z-methyl-benzselenazole ethiodide with e-N- methylphenylimido-u-N-methylphenylamido-a.-y-

pentadiene hydrobromide in the presence of an amount of triethanolamine not greater than the quantity equivalent to that of said base, and condensing the intermediate product thus obtained with lepidine iodo ethylate in the presence of triethylamine.

5. The process of producing [3-ethy1-benzthiazole- (2) l[3-ethyl{naphtho-2'.1:4.5-thiazole}- (2) -5-methylheptamethinecyanine iodide which comprises reacting on 2-methylbenzthiazole ethiodide with e-phenyl-imido a-phenylamidomethyl-axy-pentadiene hydrobromide in the presence of an amount of piperidine not greater than the quantity equivalent to said base and condensing the intermediate product thus obtained with 2-methyl- {naphtha-2 .1 :4 .B-thiazole} -ethiodide in the presence'of diethylamine.

WALTER ZEH. 

